Fig 1.

Operating characteristics for hypothetical dose-toxicity curves and initial dose-toxicity curves in a trial design with 10 dose levels. The initial curve (dashed line) is what the model relies on as a starting assumption (tuning parameter), whereas the accumulated data override this initial curve and fine tune the location of the MTD based on an adaptive re-estimation. Actual dose-toxicity curve (solid line) is the true underlying dose-toxicity curve that is unknown at the design stage. Trial designs (A) 1, (B), 2, (C) 3, and (D) 4, as listed in Table 1. DLT, dose-limiting toxicity; Pts, patients.